1. Field of the Invention
The present invention relates to a radiation imaging apparatus, a drive method therefore and a program of the radiation imaging apparatus.
2. Description of the Related Art
In recent years, a planar radiation imaging apparatus using semiconductor manufacturing technology has been developed as a radiation diagnostic apparatus. Such planar radiation imaging apparatus includes an indirect conversion type, which converts X-rays to visible light with a phosphor for detection with photodiodes arranged in a matrix, and a direct conversion type, which directly converts X-rays to electric charge by the photoelectric effect using amorphous selenium for detection.
The radiation diagnostic apparatus requires a high contrast resolution for doctor's diagnosis. However, there is a several hundred times difference between dosages of X-ray used for fluoroscopy and those used for radiography. Therefore, the bit range of an AD converter cannot be effectively utilized. U.S. Pat. No. 6,163,029 has proposed an improvement measure.